Migration of the Gray Whale

Updated on May 8, 2016

Gray Whale

Gray Whale | Source

The gray whale is a marine mammal which migrates once every year between feeding grounds in the arctic to breeding grounds in the warms waters of Baja California, Mexico. These whales spend most of the summer season feeding in the freezing waters of the north pacific, and then, in October, as the ice begins to form in the ocean, they begin to displace in small groups along the western coast of Canada the United States and Mexico, Finally, arriving to the lagoons in Baja California peninsula, where they will mate and give birth to their calves.

Gray Whale Description

The gray whale is is not totally gray, but of a gray-dark hue and is covered by gray-white markings, or scars produced by parasites. They possess two blowholes on top of the head with which they create a distinctive V shape on the surface of the water.

New born Gray whales may reach from 5 meters (16.4 feet) and adults from 13-15 meters (43-49 feet); however, females are usually larger than adult males. A mature gray whale may reach a weight of 40 tons. Gray whales usually live from 50-70 years of age.

The gray whale uses a baleen which is used to filter food. It is located in the upper jaw of the whale and it helps trap food such as krill after water has been filtered out of the whale´s mouth. protuberancias

Another feature in the whale are small depressions which contain a lone stiff hair in the upper jaw. The whales head lacks the prominent furrows which are characteristic of other rorquals, instead displaying shallow furrows under the throat.

The gray whale does not bear a dorsal fin, instead show protrusions in the middle of its rear quarter, which is known as the dorsal ridge. Its tail may be 3-3.5 meters transversly and intensely jagged at the center, while the edges narrow down to a point.

Adult Gray Whale

Gray Whale | Source

Migration of the Gray Whale

Gray Whale Migration | Source

Gray Whale Migration Route

It is believed that gray whales travel night and day at an average speed of 8 km per hour (5 miles) per hour. At this average speed, they may cover 120 km (74 miles) of distance a day. They may swim anywhere from 17,000-22,000 km (10,500-13,700 miles) on a round trip, which is believed to be the longest trip made by any group of mammals.

It has been discovered that they may take naps of between 10-20 minutes while swimming. They may do this by using a mechanism compared to auto-pilot in any system. It is by the end of December and beginnings of January that the whales begin to reach their destination at the lagoons of ¨Laguna Ojo de Libre, San Ignacio and Magdalena.¨

The gray whale starts its migration by the month of October, as the ice begins to form and pushes them southward from their feeding grounds. The two to three moth migration starts in the Bering and Chukchi seas and ends in the warmer lagoon waters of Baja California, Mexico.

In the last days of December and the early days of January, the whales begin to arrive to the lagoons in the Mexican peninsula. The lagoons where the gray whales are most often found are Laguna Ojo de Liebre, Laguna de San Ignacio and Laguna Magdalena.

By the middle of February to March, most of migrating whales have replenished the lagoons, which provide the perfect grounds for mating, breeding and of new born calves. The first whales to be seen are the pregnant ones along with the females experiencing oestrus.

During the last days of February and the whole moths of April and March, whales begin to leave the lagoons heading north of the Pacific. The first to leave the lagoons are the males and females who did not breed new borns. The last to leave the lagoons are pregnant whales and mothers with a new baby whale, only when the calf is able to do the long trip north.

Baja California, Mexico

Baja California, Mexico | Source

Gray Whale´s Mating and Breeding Grounds

Both male and female adult gray whales reach puberty at the age of eight years old. Females usually experience oestrus in the last days of November and early December, during which males show an increase in testes mass. Females usually mate with various males. The gestation period lasts from 12-13 moths. Mating and breeding usually occurs in the shallow and warm waters of Baja California, Mexico. So, when the gray whales leave the shallow water, either, the females already carry a fetus with them or gave birth to a calf.

It is in the latter half of the pregnancy when the fetus experiences a rapid increase in length and body mass. At birth, a calf measures 4 meters (13 feet) At seven months calves are weaned and dependence from her mother is diminished.

Gray whale females undergo single ovulation period and until now, only sparse events of twin births have been reported. It is believed that the shallow water of the lagoons in Baja California, Mexico provide them with natural protection from sharks and Orcas.

Mostly Feeding in the North Pacific and Rarely while Migrating

They use the food gathered by filtering with the use of a baleen in the upper jaw. Most commonly the gray whale feeds on the north Pacific and only rarely during its migration to warmer waters, relying principally on their large fat reserves

The gray whale usually feeds from crustaceans which it would eat by twisting to the right side, with results in the loss of eyesight. They also feed by gathering sediments from the ocean floor and using the protein contained in them. baby whale may drink approximately 720-1135 liters (190-300 Us gallons) of the mother´s milk every day.

Gray Whale Watching

For those who want to witness the gray whale migration, there are touristic organizations that provide tourists the opportunity to watch the gray whale migration from the shores of main ports, such as San Diego or Monterrey and Morro bays.

Along these places, the gray whale migration can also be seen from the earliest days of April to the last days of March when they return to the cold waters of the North pacific.

Gray whales can be seen from any coast, as they usually travel around 4 km (2.5 miles) from the shore line.

Threats to the Gray Whale

Threats to the gray whale´s population include human activities in the lagoons, in Mexico, global climate change, toxic wastes into the ocean, entanglement into fishing equipment, oil extraction and exploration.

Another threat to the gray whale is whale hunting and predation by their natural enemy, the Orca.

Additional Information

Their name (Gray Whale) derives for the gray patches and white spotted

The gray whale is the surviving species of in the genus Eschrichtius

The gray whale is a descendant from filter feeding whales common at the beginnig of the Oligocene period, more than 30 million years ago

The gray whale is distributed mostly in the north pacific, although, rarely in the north Asian side of the Pacific

The population which once lived in the north Atlantic were extinguished before 500 AD off the European coast and from 17th-18th centuries in the American coast

On May 8, 2010, a gray whale was seen in the Mediterranean Sea

A gray whale was spotted off the coast of Namibia, South Africa

The gray whale migration on a round trip with around 22,000 km (13,700 miles) is the longest known mammal migration in the Pacific Ocean

The gray whale migration has given scientists new insights into how endangered species lifestyle may be contributing to their survival

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